Telephone-exchange system.



E. H. SMYTHE. TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED JUNE 8, 1915.

1 ,227,01 O. Patented May 22, 1917.

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TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE 8. 1915- 1,227,01.0.' Patented May 22, 1917.

3 SHEETS-SHEET 2- HI.

WE W 1 I Q Q m E. H. SMYTHE.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED JUNE 8. I915.

1 ,227,01 0. Patented May 22, I917.

3 SHEETS-SHEET 3 l Fl" N f N Mi-0 "3 l j w ll Q 'H" ing To all whom it may concern.

- Illinois,

n11 Improvements in uni En TA ES PAT NT oE roE.

EDWINH. .SMY HE, or onroaeo, ILLINOIS, AssIGNoE, BY MEsNE ASSIGNMENTS, To I WESTERN ELECTRIC COMPANY, INooaronATEn oonroRATmNoE w YORK.

TEEErHoN -EXC ANGE SYSTEM.

Application filed June 8, 1915. Serial No. 32,844.

Be itknown that. I, ED IN H. SMYTHE, a citizen ofthe United States, residing at Chicago, in the county: of Cook and State of have invented certain new and use- Telephone Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to an improvedeorganization for use in telephone exchange systems, and is particularly directed toward an improved system for the control of devices employed in connectionwith telephone connecting circuits'.-Its particular object is to provide means for automatically controlling the connection of a device,"such as the Source ofringing current, with one end or the other ofa telephone connecting circuit. T y

' One end of a telephoneconnecting circuit is ordinarily used for answering the calling subscriber, and the other end for completing connection with the called subscriber. It is to the last mentioned or calling end of the connecting circuit that the'ringing or calling current is usually applied. 1 But it occasionally is necessary to apply ringing current to the answering end of the circuit; as, for instance, whenthe called subscriber is slow in responding and the calling subscriber before he has answered; or when the called subscribers line is found busy, and the operator is instructed to signal the callsubscriber as soon as thecalled line is disengaged. This invention is primarily for the purpose or automatically directing the application of ringing current toward that end of the connecting circuit where the connected subscriber has his telephone on the hook, andfor facilitating the operation of ringing. back upon the-connecting circuit. when the called subscriberis at his telephone and the calling, subscribers telephone hung up, and is air-improvement upon'thesystemv disclosed; in the application of .Henry, P. Olausen, Serial Number 18,459, filed April 1, 1915.\

The invention will be more particularly. described by reference to i the accompanying drawings, in which Figure 1 illustrates the invention as applied to an ordinary two-wire connecting cord circuit; Fig.2 shows a modification adapted foruse in connection with a system involving party lines, and ,Fig."3 shows a further modification with respect-to the manner in which the condition of the ringing current to one end or connecting circuit. I Referring particularly to Fig. 1, A and B r are thecalling and called subscribers stations, respectively, and C is the connecting circuit adapted for uniting the lines extending from the two stations to the central office. Each of the stations may have the the other of the and a bell or ringer3, and may beconnected with the central, office by a pair of line con- ,ductors :4. and 5, said conductors at the central office extending to the usual line terminal apparatus including spring jacks 6, line relay 7 and cutoff relay 8. The line relay 7 operates to light the line lamp 9 when the subscribertakes his telephone from the hook, andis disconnected from the line circuit by the operation of the cutoff relay 8, in the psual way, when connection ismade with the Theconnecting cord circuit terminates in an answering plug 10 and a calling plug 11, the two conductors 12 and 13 of the cord circuit terminatingin tip and ring contacts, respectively, of the two plugs, and including condensers 14 to divide the two'halves of the circuit conductively. -Associated with the answering half of the cord circuit are the tip. and ring supervisoryrelays 15 and 16, respectively, and associated with the calling half of the cord circuit are the tip and ring supervisory relays 17 and 18. Each of these pairs 01": relays is connected in a bridge of the cord circuit including the central battery 19,, the relays of control the associated answering and calling supervisory lamps 20 and 21 inthe usual way. That is, the energizing circuit of each lamp is controlled in contacts of the ring supervisory relay which are normally open, and in contacts of the tip supervisory relay which are normally closed eitherplug is inserted into a spring j ack the resultant actuation of the associated ring supervi'sory relay completes, the circuit to place control "of the corresponding tip supervisory relay, which is deenergized to close theilamp circuit or energized to complete it, depending upon whether the responding station is on or off its hook.

The connecting cord circuit is provided with a listening key 22 by means of which usual equipment, including a switch hook 2 I a sweater a Letters Patent. I P t t d a 22,1917,

connected lines controls the application of V the; associated supervisory lamp under the telephone at the corthe operator is enabled to bring her telephone set into connection with the circuit in the usual way; and with a ringing key 23 which, when depressed, cooperates with other devices to apply calling current to the circuit for ringing either the called or the calling subscribers bell in a manner now to be described.

The cord circuit is provided with two electromagnetic ringingkeys or relays 24 and 25, the relay 24 being adapted when operated to interrupt the cord circuit and connect to a source of ringing current 26 the portion of the cord circuit extending to the answering plug 10; while the relay 25 is adapted when operated to interrupt the cord circuit and connect with the source of ringing current the portion of the cord circuit extending to the calling plug 11. These electromagnetic ringing keys or relays 24; and 25 have an energizing circuit that is operatively connected with one or the other of them, and which is controlled by the operators ringing key 23 and the answering and calling supervisory relays 15 and 17 operating jointly. This energizing circuit is a divided circuit having two branches, the undivided or common portion 27 of the circuit including the contacts of the operators ringing key 23, and the two branches 28 and 29 including the windings of the answering electromagnetic ringing key 24 and the calling electromagnetic ringing key 25, respectively.

The two branches of the energizing circuit are alternatively connected with the common or undivided part of the circuit in the contacts of relay 30', the energizing circuit for which relay is controlled in contacts of the answering supervisory relay 15 and the calling supervisory relay 17. T'Vhen the relay 30 is inert, the branch 29 of the energizing circuit, including the winding of the calling electromagnetic ringing key 25, is under the control of the operators ringing key 23; while when the relay 80 is actuated the other branch 28, which includes the winding of the answering electromagnetic ringing key 24:, is under the control of the operators key 23.

ether or not the relay 30 connects one or the other of these branches with the operators key is dependent upon the condition of the answering and calling supervisory relays 15 and 17, and therefore upon the condition of use or disuse of the calling and called lines with which the supervisory relays l5 and 17 are respectively associated. The energizing circuit of the relay 30 includes back contacts of the relay 15 andfront contacts of the relay 17. In order, therefore, that the relay 30 be energized, it is necessary that the answering relay 15 be inert and the calling relay 17 be operated; that is, that the calling subscribers telephone be hung up and the called subscribers telephone be off its hook. When this condition exists the relay 3O closes its front contacts and places under the control of the operators key the branch of the energizing circuit which includes the winding of the answering electromagnetic ringing key 24. At other times, the relay 30 is inert, and the branch of the energizln circuit, including the winding of the calling electromagnetic ringing key 25, is under the control of the operators ringing key 23.

racing, now, the operation of the embodiment of this invention illustrated in Fig. 1, when the calling subscriber A takes his telephone from its hook, he lights his line lamp 9 at the central office, and the operator, in inserting the answering plug into the associated spring ack, brings about the extinguishinent of the line lamp in the usual way. The insertion of the answering plug closes an energizing circuit for the answering supervisory relays 15 and 16, the path for the flow of current through the tip supervisory relay 15 being by way of the closed contacts of the calling subscribers telephone hook.

The operator closes her listening key 22, and, learning that connection is desired with station B, inserts the calling plug 11 into the spring jack of the line extending to that station. This act closes a path for flow of current through the ring supervisory relay 18 by way of the cutoff relay 8 of the called line. But, as the called subscriber is not at his telephone, there is as yet no path for the flow of current through the tip supervisory relay 17 To signal the called subscriber to his telephone, the operator closes her ringing 105 key 23. This causes the energization of the calling electromagnetic ringing key 25, inasmuch as the relay 30 is inert, its energizing circuit being open both in the contacts of the actuated answering supervisory relay 15 and in the contacts of the inert calling supervisory relay 17.

To illustrate the operation of the automatic ringing control devices, it will be assumed that the called subscriber is slow in 115 answering, and that the calling subscriber hangs up in the meanwhile. The taking of the telephone from its hook at the called station energizes the calling supervisory relay 17, causing it to close its front contacts 120 included in the energizing circuit of the controlling relay 30, while the hanging up of the telephone at the calling station deenergizes the answering supervisory relay 15, causing it to close its back contacts in- 5 cluded in the energizing circuit of the controlling relay 30. The relay 30 is therefore energized, and closes its front contacts to bring the winding of the answering electromagnetic ringing key 24 into circuit with 130 through the agency of theoperatorsikey 23' to whichever of the'two connected stations has its telephone hung up. i p a The modified systemgillustrated. invI ig.

2 is like the system of as being provided with two stations, A A and B B the bells at each "of, the two stations beingconnected to ground from op-' In thecentral of-" fice connecting cord are two ringing keys posite', sides of the line. 31 and 32 arranged to apply ringing current from the generator ringsides,respectively, of. the circuit.

Associated with these party line ringing keys are contacts 33 which are common to the party line. keys and are closed when w either one of them'is operated. The contacts 33play the same part in the control of the energizing circuit of the answering and calling electromagnetic ringing keys of the cord circuit 'asis played bythe operators key 23 in the system ofFig. '1. When the operator operates either one of the two party line ringing keys 31 and 32 to apply ringing current to the corresponding ringing conductor controlled by theanswering and calling electromagnetic ringing keys 24' and 25, one or the other of these electromagnetic ringing keys has its energizing circuit closed in the common contacts 33 to apply the ringing current thus determined to the calling line or to the called line, depending upon whether the controllingrelay 30 is energized or inert.

In themodification illustrated in Fig. 3,

the alternative energizing paths for the answering electromagnetic ringing key 24 and the calling electromagnetic ringing key 25 are controlled directly in contacts of the answering tip supervisory relay 450 and calling tip supervisory relay 41, instead of indirectly through the medium of a controlling relay such as 30 of Fig. 1 and Fig. 2. The energizing circuit magnetic ringing key 25 extends through I back contacts of the calling supervisory relay 41, while the energizing circuit for the answering electromagnetic ringing key 24 extends through front contacts of this relay and back contacts of the answering super-1 visory relay 40. Both of these energizing circuits also include the normally open contacts of the operators' rmging 1', excepting that y it is equipped for party line operation. The calling and called lines are each illustrated gization '26 to the tip and calling and answering supervisory relaysof the calling electro-V energizing circuit key 23. I When the telephone at the called station is I WVhen hook and the telephone at the calling station is hung up, the consequent energization of the relay al and de'energization of the relay l0 closes the path for the energization of .the answering electromagnetic ringing key 24, so that the closing of the operators key 23 brings about theapplication of ringing current to the calling line.

' "What is claimed is:

- 1. 'Ina telephone connecting cord circuit, the combination with a device normally associated with one end of said cord circuit, of an'electromagnetic switch for associat .ing 'said device with the other end ofsaid cordcircuit, a key for controlling theener of said electromagnetic switch,

connected with said connecting COIClCiIfClllt,

and contacts of said relays jointly partici pating in the control of said electromagnetic switch.

2. In a telephone connecting rod circuit having an answering and a calling supervisory relay, the combination withca device normally adapted'for connection with the calling end of said circuit, of an electromagnetic switch adapted when operated to associate said device with the answering end of said circuit, a controlling key, and an energizing circuit for said electro-magnetic switch under the joint control of said controlling key and said supervisory relays.

.3. In a telephone connecting cord; circuit having an answering and a calling supervisory relay, a source ofringing current normally adapted for application to the 'callingend of said connecting circuit, an

electromagnetic ringing key adapted when operated to apply ringing current from said source to the answering end of said connecting circuit, a manually operated switch .and an energizing circuit for said electrofl key controlled jointly by magnetic ringing said manual switch and said supervisory relays. l 4. In a telephone connecting cord. circuit having an answering and a calling supervisory relay, a source of ringing current, an electromagnetic ringing key adapted when operated to apply ringing current from said source to the answering end of said connecting circuit, a controlling key and an for said electromagnetic ringing key under the control of normally open contacts of said controlling key and calling supervisory closed contacts of visory relay.

5. In a telephone connecting cord circuit said answering sup errelay and normally 7 having an answering and a calling supervisory relay, a source of ringing current, an answeringand a calling electromagnetic ringing key, each of said keys being adapted when operated to apply ringing current from said source to its respective end of said connecting circuit, a controlling key, an electromagnetic switch having an energizing circuit including normally open contacts of said calling supervisory relay and normally closed contacts of said answering supervisory relay, and an energizing circuit for said electromagnetic ringing keys, said energizing circuit having a branch closed through said calling electromagnetic ringing key in contacts of said electromagnetic switch closed when said switch is inert, a branch closed through said answering electromagnetic ringing key in contacts of said electromagnetic switch when said switch is energized, and having a common portion closed in contacts of said controlling key when said key is operated.

6. In a telephone connecting cord circuit having an answering and a calling supercoples of this patent may he obtained for five cents each, by addressing Washington, D. 0."

Visory relay, a source of ringing current normally adapted for application to the calling end of said connecting circuit, an electromagnetic ringing key adapted when 0 erated to apply ringing current from said source to the answering end of said connecting circuit and prevent its application to the calling end of said circuit, an operators key, and an energizing circuit for said electromagnetic ringing key controlled jointly by said operators key and said supervisory relays.

7. In a telephone connecting cord circuit having an answering and a calling supervisory relay, a source of calling current, an electromagnetic ringing key for each end of said connecting cord circuit, an operators key, and an energizing circuit for each of said electromagnetic ringing keys controlled jointly by said operators key and said supervisory relays.

In witness whereof I hereunto subscribe my name this 5 day of June, A. D. 1915.

EDWIN H. SMYTHE.

the Commissioner of Patents, 

